Feeding of internal-combustion engines



March 18, 1952 M. C. CARBONARO FEEDING OF INTERNAL-COMBUSTION ENGINESFiled June 14, 1947 4 Sheets-Sheet l March 18, 1952 M. c. CARBONARO2,589,536

FEEDING OF INTERNAL-COMBUSTION ENGINES Filed June 14, 1947 I 4Sheets-Sheet 2 March 18, 1952 M. c. cARBoNARo 2,589,536

FEEDING OF INTERNAL-COMBUSTION ENGINES Filed June 14, 1947 4 Sheets-Sheet 3 March 18, 1952 M. c. CARBONARO FEEDING OFINTERNAL-COMBUSTION ENGINES 4 Sheets-Sheet 4 Filed June 14, 1947Patented Mar. 18, 1952 UNITED STATES PATENT OFFICE FEEDING OFINTERNAL-COMBUSTION ENGINES Marius Clement Carbonaro, Paris, FranceSection 1, Public Law 690, August 8, 1946 Patent expires December 14,1964 -9 Claims.

In the usual carburetors:

(at) The mixture is generally too rich when running at reduced load inconsequence of the addition of the delivery of the power jet and that ofthe idle-jet.

' b) The atomization is uneffective as the airspeed in the venturipreceding the throttle is too low.

The mixture of air and fuel is imperfect on account of the condensationstaking place on the throttle arranged across the carburetted air stream.

These faults produce a defective distribution of the mixture between thecylinders in consequence of the separation of the liquid from the air,produced by the bends in the intake manifold.

In the process which is the subject of the present invention thesedisadvantages are avoided by utilizing one or more of the followingessential arrangements.

(1) The intake air stream runs across two successive and distinctconstructions, the first of which is hereinafter termed the upper orup-stream venturi, and is arranged before the throttle, and the second,termed hereinafter the lower or downstream venturi, is arranged afterthe throttle.

(2) The diameter of the lower venturi is smaller than that of the upperventuri, so that the depression or partial vacuum prevailing there isalways greater than that produced in the first.

(3) An auxiliary conduit designated hereinafter by the term primaryby-pass communicates through its two extremities with the constrictedsections of the two venturis mentioned above by means of two calibratedorifices designated hereinafter by the names upper or up-stream orificeand lower or downstream orifice respectively.

(4) These two orifices are of unequal crosssections the upper orificebeing always much larger than the lower orifice, so that the depressionprevailing inside the primary by-pass is always'approximately equal tothat prevailing'in the upper venturi.

(5) The fuel is fed, at all speeds of the engine; through a nozzle orjet discharging into the primary by-pass andsupplied by a constantlevelfioat tank of the usual type. The delivery of this jet may be correctedby known means, such as flooding or air injection.

, (5) -The;;mixture or emulsion'obtained in the primary by-pass throughthe mixing of the liquid fed through the jet with the air circulating inthis by-pass receives a new addition of air to improve the atomizationby linking the lower orifice not to the lower venturi but to a secondaryby-pass shaped also to the form of a venturi, connecting thenon-constricted part of the intake manifold below the throttle with theconstricted section of the lower venturi.

(7) The effectiveness of the atomisation occasioned by the secondaryby-pass may be considerably increased by substituting for the saidby-pass an atomisation air compressor of the dry type or of the wettype, the suction of which branches out of the intake manifold of theengine beyond the throttle, and the discharge of which likewise deliversbeyond the throttle. The primary by-pass then communicates through itsdown-stream orifice with a constriction in the form of a venturiprovided on the outlet or on the inlet of the said compressor.

(8) The above mentioned compressor may be replaced by a supply ofexhaust gas picked from the exhaust manifold and brought to expand intoa tube shaped into the form of a venturi the said tube discharging intothe intake manifold beyond the throttle, the primary by-pass leading tothe constricted section of this said venturi.

(9) In view of correcting at low speeds the excessive flow from the mainjet due to an excessive vacuum in the secondary by-pass, the fourfollowing means may be employed, separately or in combination.

(a) An adjustable calibrated orifice opening in the atmosphere isarranged between the downstream orifice of the primary by-pass and thesecondary by-pass providing so a means of modcrating the effect of thissecondary by-pass at low engine speeds.

(b) The cross-section of the down-stream orifice is made variable, bymeans for instance of a suitably profiled movable needle, this needlebeing operated for example either mechanically by rod-and-levermechanism bound to the position of the throttle, 0r pneumatically bymeans of a member sensitive to the vacuum prevailing in the atomizingventuri;

(c) The cross-section of the nozzle or jet is controlled for instance bymeans of a suitably profiled movable needle this needle being operated,as indicated in the above paragraph (b) either mechanically by means ofrod-and-lever mechanism bound to the position of the throttle orpneumatically bymeans of a mem- 3 ber sensitive to the vacuum prevailingin the atomizing venturi.

(d) The difference of pressure under which the nozzle or jet delivers isreduced, for instance by utilizing the partial vacuum that prevails inthe down-stream venturi.

In particular, it is possible to obtain this reduction by bringing intoaction upon the level of the liquid in the float chamber an opposingvacuum, which, for low speeds, is substantially equal or bears asubstantially constant ratio to the vacuum induced in the primaryby-pass by the atomizing venturi or the like.

This opposing vacuum may be obtained by connecting the fioat chamber toan auxiliary chamber provided with an inlet orifice cand with an outletorifice, the cross-sections of which are in the same or approximatelythe same ra tio as those of the up-stream and down-stream orifices ofthe primary by-pass, the smaller of these orifices being subjected tothe vacuum created by the atorniaing venturi. In this case t e kin el reytne noz e-e ie t n d in the above paragraph (5) will have to be takenfrom the float chamber, order that the amou of the aid brakin ai may beindep nden of he abo e mentioned o p in vacuum.

(10) In view of temporarily enriching the mixtu in o d r to fac i tstart n the vacuum its control thus playing the part devolved to start-.t n sual eerbnret ren v ew to enr ch the mixtur for ta Oil conditions amechanical connection may be established ween t e. m able ne dlementioned in the receding'para raph and he throttle so as to reduceautomatically the cross-section of pb nrn 0 1: ce when the throttlereaches its fully pen posit 7 (12) By Way of modification of the generalaran ments indicated above, in a multi-cylinder engine, there is onlyone up-stream venturi to serve for measuring the quantities, whereasthere may be a plurality of down-stream venturis, at the rate of one percylinder, or one per intake port common to two cylinders, The primary.bypasses the number of which is equal to the number of down-streamventuris, each provided with its own jet fed by a common float chamber,comm'unicate by their up-stream orifices with the constrictedcross-section of the up-stream venturi and by their down-stream orificeswith the various down-stream venturis, each provided with its ownsecondary by-pass.

Various embodiments of carbureters according to the present inventionare illustrated by way of example, in the accompanying drawings, inwhich:

Figure l is a fundamental diagram of the new method of carburationproposed, comprising only a single primary by-pass.

Figure 2 is a diagram of the method of feed proposed, including aprimary by-pass, a secondary by-pass and an orifice for moderating theeffect of this second by-pass at low engine speeds.

Figure 3 and 4 show two methods of forced atomization in which an aircompressor of the r tree or oiv the wet type is substituted for thesecondary Icy-pass, the intake of said compressor being branched to theintake manifold beyond the throttle and the outlet delivering likewisebeyond the throttle.

Figure 5 shows a form of forced atomisation, in which a certain amountof exhaust gases, taken from the exhaust manifold of the engine, expandsinto a pipe in the form of a venturi taking the part of a secondaryby-pass, the restricted secv 'tion of which communicates with the lowerorifice of the primary by-pass.

Figure 6 is a diagram of a carbureter comprising an upstream venturi, adown-stream venturi, an atomizing venturi and a primary by-pass, theup-stream orifice of the latter being provided with a temporarythrottling system acting as a starter, and the down-stream orifice beingprovided with a movable needle operated by a metallic bellows subject tothe down-stream depres- 51011.

Figure '7 is a diagram of a carbureter comprising an up-stream venturi,an air-compressor of the dry type feeding the atomizing venturi, aprimary by-pass, the up-stream orifice of the latter being provided witha temporary throttling system acting as a starter, the float chamberbeing subjected to the effect of an opposing depression obtained from anauxiliary chamber in permanent communication with the atomizing venturiand provided with an inlet orifice and an outlet orifice suitablyselected, the braking air of the main nozzle or jet being obtained fromthe float chamber.

Figure 8 is a diagram of the method of carburation proposed applied to afour-cylinder en gine and embodying a single upper diffuser with twolower diffusers and two separate primary and secondary by-passes.

In Figures 1, 2, 3, 4, 5 and 8 the same elements are denoted by the samereference numerals.

Referring to Figure 1, the carbureter which is the subject of theinvention comprises essentially a float chamber l, in which a float 2controls the petrol inlet 3. This chamber is opened to the atmospherethrough an orifice 4, and supplies a jet or nozzle 9. The body of thecarbureter comprises an intake pipe 5 containing a first venturi 6arranged above or on the up-stream side of the throttle 1 and a secondventuri 8 arranged below or on the down-stream side of the saidthrottle. The constricted section of the lower venturi 8 is markedlysmaller than the constricted section of the upper venturi 6, to such anextent that for any given air delivery, the vacuum prevailing at 8 isalways higher than that prevailing at 6. V

The constricted sections of the upper and of the lower venturis areconnected to each other by a primary by-pass I I communicating with thesaid constricted sections through an upper orifice i2 and through alower orifice l3, the orifice 13 being much smaller than the orifice I2.

The working of the arrangement is as follows: For any opening of thethrottle 1, the vacuum prevailing in the primary by-pass H isapproximately equal, at all speeds, to that prevailing in the venturi 6,because the orifice I2 is much larger than the orifice I3.

It follows that the delivery of the jet 9 is approximately equal to thatwhich it would have if it opened into the upper venturi. However thevacuum acting at 13 being stronger than that acting at I2, thecirculation in the conduit H takes place in the direction from I2towards l3. The liquid supplied by the jet '9, supplemented 5 with acertain quantity of air, arrives in the state of a mixture or emulsionin the body of the carbureter at the constricted section of the lowerventuri 8. It is mixed there with the main amount of air sucked by theengine and then proceeds to the intake valves of the engine.

The mixing of the intake air with the emulsified fuel has thus beenefiected below the throttle, the metering being ensured, as in anordinary carbureter, by the combined action of a constant-level tank anda jet with the upper venturi.

It should be observed that for the same engine speed the depressionacting on the lower orifice l3 continues to increase as the throttlecloses, while it decreases on the upper orifice l2. For atomizing thefuel supplied by the jet 9, there is then available an increasingdifference of pressure between l2 and 13, which increases the quantityof atomizing air at low speeds, contrary to the usual working of thecustomary carbureters, in which the atomization is not carried so far atlow speeds.

Figure 2 shows an alternative form of the ar-. rangement represented inFigure 1, in which the primary by-pass ll does not end at theconstricted section of the lower venturi 8 but at the constrictedsection of a secondary by-pass l5, connecting the body of the carbureterbelow the throttle with the constricted section of the venturi 8. Thissecondary branch has the profile of a venturi and the confluence of theprimary bypass and the secondary by-pass coincides exactly with theconstricted section of the said venturi.

The liquid supplied by the jet 9 therefore receives a first addition ofair in the primary bypass and then a second addition of air in theventuri. It is atomized a third time through mixture with the mainamount of air in passing into the lower venturi.

In the arrangements described above, the dif ferences of pressureavailable for atomization range from a few centimeters of water headwhen running at full load to half an atmosphere when running idle,thereby enabling much better atomization than in standard carburetors,the latter having available pressure differences ranging merely fromzero to a few centimeters of water head. With the foregoingarrangements, however, it is not possible to equal the atomizationobtained through direct injection systems by means of injectionpressures reaching values from 10 to 200 kilograms per squarecentimeter.

The fact that in the device described above thefunctions of metering theliquid and of atomizing are effected by the primary by-pass and by thesecondary by-pass respectively, however, enables this result to beobtained.

The fuel metered into the primary by-pass may undergo a pneumaticatomisation under stron pressure in the secondary by-pass by interposingin this latter an air-compressor driven by the engine. The presence ofthis air-compressor, which may be of the rotary type or of the pistontype, does not introduce any disturbance into the feeding of the engineor into the quantity of air that passes through the upper venturi,provided the intake and the delivery of the said compressor are bothbelow the throttle. The amount of air that traverses the compressor isalways a cons'tantfraction of the total amount of intake air drawn in bythe engine, as they rotate at proportionate speeds and are supplied atthe same pressure,

6 Figures 3 and 4 are two alternative forms of this arrangement. In Fig.3 the compressor 11 of the dry type, is only traversed by pure air, the

(atomization taking place after the compressor.

This solution is applicable to all fuels. The compressor I1 is drivenfrom the engine by means of a belt I'la. I

In Figure 4, the compressor I1 is of the wet type, and is traversed by amixture or emulsion of air and fuel. The compressor is driven from theengine by means of a belt (not shown in Fig. 4). The atomization takesplace partially before the compressor and partially after it, throughthe medium of, an injector of suitable profile. This solution isapplicable to fuels which act to a slight extent as lubricants, such asgas oil the flow of which through the body of the compressor does notinvolve any danger of affecting the latter.

Practically, the capacity of the atomizing compressor is of the order ofone twentieth of the capacity of the engine; the outlet pressure is ofthe, order of from 0.5 to 1 kilogram per square centimeter, according tothe degree of constriction of. the outlet orifice.

The essential advantage of the pneumatic atomization thus obtained ascompared with the mechanical atomization of direct injection is that alow-pressure air-compressor without any metering function is substitutedfor a high-precision injection pump, which is a great deal more costlyand difficult to manufacture.

Instead of producing the compressed air for atomization by a mechanicalcompressor, it is possible to use exhaust gases under pressure takenfrom the conduit [9 in the exhaust pipe I8 common to all the cylinders.These gases at a high pressure and a high temperature supply a venturil5 constituting the secondary by-pass. This arrangement is showndiagrammatically in Figure 5.

It has been admitted above that by suitably selecting the relativecross-sections of the upstream and down-stream orifices of the primaryby-pass the depression or partial vacuum in the latter is substantiallyequal at all speeds to that prevailing in the up-stream venturi. Inmatter of fact this equality is only approximate, particularly when theengine runs idle. It may therefore be advantageous to adopt correctivearrangements.

Thus in the arrangements illustrated in Figures 2, 3, 4 and 5 theexcessive delivery of the main jet as low loads occasioned by the excessive vacuum then prevailing in the secondary bypass (on account of theutilization of the venturi [5, which has the effect of increasing thedepression at the orifice I3) is corrected by menas of a needle screwl6, which, permitting an admission of air from the exterior, providesthe possibility of reducing at will the vacuum acting upon the orificeiii. The screw l6 thus enables the richness to be regulated at idlingspeed. f Figures 6 and 7 illustrate two other solutions of the problemof idling, consisting in acting directly upon the supplementarydepression in duced. when idling in the primary by-pass by the atomizingventuri. y

In Figure 6, the float chamber la feeds a sub-' merged jet 9acorrectedby an injection of air in stages, coming from a corrector Mia.The emulsion duct l9a opens into the primary by-pass Ila, whichcommunicates on the one hand with the up-stream venturi 6a. and on theother hand with of the throttle la.

the atomizing venturi I8c, co-opera'tingwith the down-stream venturi 8a.The n l-stream orifice lid andthedown stream orifice I311 control thecirculation of air in the by-pass I Ia. The downstream orifice I3a'is;controlled by a movable needle Ila; actuated by metallic bellows Ifia,subjected internally to the action of the vacuum created at low speedsby the venturi iBa.

This device operates in the following manner: When'starting, the vacuumcreatedby the venturi l8cis considerable on account of the closure Theneedle I-Ia penetrates into the orifice I30. and diminishes thecross-sectionythereof, thereby moderating the vacuum induced in theby-pass.

As the throttle la is opened more and more, the needle Ila returns toits initial position, thus opening the orifice' Isa wider and wider,-and thereby leaving a larger and larger'passage for the-emulsiondelivered by the duct Iii/1.

The control of the down-stream orifice might be effected in variousother ways, in particular 'by'amechanical control of the throttle istransmitted to the needle by any convenient means.- A method of controlanalogous to that of the down stream orifice is applicable to theorifice of the: jet 9a.

It is often useful to be able to enrich the carburetted mixturetemporarily at the time of starting- This result can be obtained,according to the invention by temporarily reducing the cross-section ofthe up-stream orifice. To this end the orifice I2a may be partiallyobstructed at the time of starting by a movable needle 22a, returned toits starting position by a return spring, and operated by a startingpull member, not shown, or else by a member sensitive to the temperatureof the engine orof the water jacket. As soonas the. starting has beeneffected the pull member controlling the needle 22a is released and thedepression at I Ia falls back to itsorig-inal e, corre ponding to thevalue selected for The movable needle-22o. may likewise be utiliced toOccasion the supercharging of the engine at -full power by means of anysuitable connection between the throttle and the needle, enabling areduction'to be effected in the crosssection-of the upstream orificewhen the needle reaches substantially the fully open position.

In Figure '7 the carbureter comprises a float chamber Ib in which afloat Zbcontrols the petrol inlet 3b. This chamber communicates by aduct 41; with the auxiliary chamber IIb, which is in communication by anorifice 281) with the open air and by an orifice I 6b with the atomizingventuri. emulsion chamber Illb, which is supplied with braking airthrough an orifice I5b, which is connected by a duct 23b with the floatchamber, This figure also includes the Lip-stream venturi 6b, theprimary by-pass I ll), controlled by. the up-stream orifice I21), andthe downstream orifice I3b, the atomizing venturi Nib, fed by thecompressor 2 lb driven from the engine by means of a belt He, the inletside of which is connected with the intake pipe 5b of the up-streamcarbureter of the throttle 'Ib', and finally the starter 2211.

With the arrangement adopted, the braking effect produced by the airpassing through the orifice [5b upon the out-flow from the jet 9b isindependent. from the opposing depression induced upon the. floatvchamber, because this opposing depression acts at the same time upon Thejet 9b delivers petrol into the 8 the braking orifice I5b on the onehandand upon the jet so on the other hand.

It will be quite understood that the metho of correction of the flow ofbraking air described above is applicable to all the modificationsof thecarbureter according to the present invention in which an opposingcorrectional depression is caused to act upon the float chamber, whethera down-stream venturi combined with a vacuum booster, or a compressor ofthe dry or wet type isemployed for feeding the atomization venturi, orfinally whether a part of the exhaust gases is used for feeding thissame venturi. v

Figure 8 is a diagram of the application of the arrangements illustratedin Figures 1 and 2 to a four cylinders engine. In this diagram, each ofthe two intake ports is provided with its lower venturi 8. To each ofthese two venturis' there leads a secondary by-pass such as I5,constituted by a venturi acting through it's constricted sec: tion onone of the two primary by-passes such as II. The two jets 9 are suppliedby acommon float chamber tank 1. The single upper venturi 6 acts on thetwo upper orifices 2 of the two primary by-passes. The throttle 7controls the intake manifold M interposed between this throttle and thetwo intake ports of the engine.

This arrangement makes possible to control the richness of the mixtureseparately on each group of two cylinders. It can be extended to thecase in which the four intake valves are installed in four differentports. There is? then the possibility of separately adjusting. the.richness in each cylinder by acting on each of the four correspondingjets.

If in the application of the "invention to a multi-cylinder enginetheatomization is of the air-compressor forcedtype, the followingprocedure may be adopted: if the compressor is of the dry type, and witha single body, delivery may be effected in parallel tov a plurality ofjets, if on the other hand recourse is. had to a compressorof the wettype, a compressor with a plurality of bodies will be utilized, each of.the

latter delivering its emulsion to a different in jectcr located at theentrance of an intake port.

What. I claim is:

1; Means for feeding internal combustion en.- gines comprising incombination an intake pipe; 2. throttle arranged in said pipe; a venturitube disposed in said pipe before said throttle; means for creating avacuum of a higher degree than prevailingin said venturi tube, thelatter means being disposed beyond the said throttle; a bypasscommunicating at one end With the restrict.-

ed part of said venturi tube and at the other end with said means forcreating a vacuum; and a device for supplying and atomizing fuel,delivering into the said bypass.

2. Means for feeding internal combustion engines, having a plurality ofcylinders, comprising one device for feeding fuel as claimed in claim 1per group of at least one cylinder, all said devices being fed by acommon float chamber.

3. Means for feeding internal combustion en a throttle arranged in saidpipe; a Venturi tube disposed in said pipe before said throttle; meansfor creating a vacuum of a higher degree than prevailing in said Venturitube, the latter means being disposed beyond the said throttle; a bypasscommunicating at one end with the restricted part of said Venturi tubeand at the other end with said means for creating a vacuum; two orificesof unequal cross-section disposed one after the other in said bypass,the upstream orifice being larger than the downstream orifice so thatthe vacuum prevailing in said bypass will at all times be substantiallyequal to that prevailing in said Venturi tube; and a device forsupplying and atomizing fuel, delivering into the said bypass.

5. A device constructed in accordance with claim 4 wherein the saidmeans for creating a vacuum consisting of a Venturi passage formedcoaxially in said air intake and beyond said throttle.

6. Means for feeding internal combustion engines comprising incombination an intake pipe; 3. throttle arranged in said pipe; a Venturitube disposed in said pipe before said throttle; a bypass communicatingat one end with a restricted part of said Venturi tube and at the otherend with said pipe at a point beyond said throttle; two orifices ofunequal cross-section, the said orifices being spaced apart and having arelative cross-section so that the vacuum prevailing in said bypass issubstantially equal to the vacuum prevailing in said Venturi tube; adevice for supplying and atomizing fuel, delivering into said bypass;and a device for forced atomization constituted by an air compressordriven by the internal combustion engine and drawing air from andreturning it to said pipe beyond the throttle.

7. Means for feeding internal combustion engines comprising incombination an intake pipe; a throttle arranged in said pipe; a Venturitube disposed in said pipe before said throttle; a bypass communicatingat one end with a restricted part of said Venturi tube and at the otherend with said pipe at a point beyond said throttle; two orifices ofunequal cross-section, the said orifices being spaced apart and having arelative cross-section so that the vacuum prevailing in said bypass issubstantially equal to the vacuum prevailing in said Venturi tube; adevice for supplying and atomizing fuel, delivering into said bypass;and a device "for forced atomization constituted by an air compressordriven by the internal combustion engine and drawing air from andreturning it to said pipe beyond the throttle, the atomization beingaffected beyond said compressor. v i l 8. Means for feeding internalcombustion engines comprising in combination an intake pipe; a throttlearranged in said pipe; a Venturi tube disposed in said pipe before saidthrottle; a bypass communicating at one end with a restricted part ofsaid Venturi tube and at the other end with said pipe at a point beyondsaid throttle; two orifices of unequal cross-section, the said orificesbeing spaced apart and having a relative cross-section so that thevacuum prevailing in said bypass is substantially equal to the vacuumprevailing in said Venturi tube; a device for supplying and atomizingfuel, delivering into said bypass; and a device for forced atomizationconstituted by an air compressor driven by the internal combustionengine and drawing air from and returning it to said manifold beyond thethrottle, the said compressor being traversed by an emulsion of air andfuel, the mixing of which is effected at a position preceding thecompressor.

9. Means for feeding internal combustion engines comprising incombination an intake pipe; 2. throttle arranged in said pipe; a Venturitube disposed in said pipe before said throttle; a bypass communicatingat one end with a restricted part of said Venturi tube and at the otherend with said pipe at a point beyond said throttle; two orifices ofunequal cross-section, the said orifices being spaced apart and having arelative cross-section so that the vacuum prevailing in said bypass issubstantially equal to the vacuum prevailing in said Venturi tube; adevice for,

supplying and atomizing fuel, delivering into said bypass; and a devicefor forced atomization of the fuel including an exhaust pipe and aconduit connecting said exhaust pipe to the end of said by-passcommunicating with said intake pipe at the point beyond said throttle.

MARIUS CLEMENT oARBoivARo.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,840,279 Sturm Jan. 5, 19321,892,301 Dilworth Dec. 27, 1932 1,906,982 Linga -May 2, 1933 2,102,476Mennesson Dec. 14, 1937 2,121,506 Mennesson June 21, 1938 2,283,694Perrine May 19, 1942

